Coopy is the spirited fairy companion to Yamaneko Arthur, radiating boundless energy and a playful charm. Her lively interactions often underscore her mischievous yet endearing personality, exemplified when she flushed vividly at the sight of Dancho Arthur in a pink apron—a reaction distinct from other Arthurs and their fairies. In battle, she demonstrates fierce loyalty, leaping to shield Bodach from Arthur Aqua’s Aqua Ball with her body, arms outstretched protectively behind him.

Her striking appearance features heterochromia, delicate wings, a chic hat, and a choker accentuating her neck. She dons a revealing outfit aligned with her design as a scantily-clad figure. Though primarily a support figure for Yamaneko Arthur, she employs archery in combat, though the precise mechanics of her techniques remain undefined.